Field of the Invention
The present invention relates to a pipe joint, for example, for connecting fluid inlet and outlet tubes.
Description of the Related Art
Heretofore, pipe joints have been used for connecting fluid tubes to a fluid pressure device. In such a pipe joint, for example, as disclosed in Japanese Patent No. 3656752, after a tube has been inserted into an end of a joint main body, a nut member is gradually moved toward a central portion of a joint member by moving and screw-rotating the nut member along the tube toward the side of the joint main body, and the nut member is screw-rotated toward a displacement end position by abutment thereof against a ring member. As a result, a condition is brought about in which the tube is connected completely with respect to the joint main body which constitutes the pipe joint.
With a pipe joint constructed in this manner, by moving (screw-rotating) the nut member and by abutment thereof against the ring member, a condition is brought about in which the tube is reliably connected without leakage with respect to the joint member. However, it is difficult for an operator to visually confirm the abutment condition (connection condition) and such a confirmation operation can be performed only by judging whether or not the nut member has been moved into abutment with the ring member.
For this reason, it is extremely difficult to confirm connection of the tube with respect to the pipe joint, and in the case that a different operator attempts to confirm a connection operation that has already been performed by one operator who previously confirmed connection of the tube with respect to the pipe joint, then the same confirmation operation has to be repeated, which is troublesome.
Thus, as disclosed in Japanese Patent No. 4790035, a pipe joint is known, which is capable of enabling confirmation of a tube connection by means of the nut member itself.
With this pipe joint, a ring member is gripped between an end of the nut member and a peripheral flange that projects from an outer circumferential surface of the joint main body. On the ring member, an end surface thereof facing the peripheral flange is formed as a tapered surface, which gradually becomes inclined toward an inner circumference side and one side of the nut member.
In addition, in a state in which the nut member is separated from the peripheral flange of the joint main body, the ring member is accommodated between ends of the nut member and the peripheral flange without projecting outside beyond the outer circumferential surface of the peripheral flange. On the other hand, by screw-rotating the nut member and moving the end thereof toward the side of the peripheral flange, the ring member is pressed in an axial direction by the end, whereby the tapered surface moves gradually in a radial outward direction by abutment thereof against the peripheral flange, so that the tapered surface projects outside with respect to the outer circumferential surface of the peripheral flange. Owing thereto, the state of connection of the tube by the nut member can be confirmed by the projection of the ring member that projects with respect to the peripheral flange.